TV This Week April 18 - 24

SUNDAY
If there was an awards show just for people who host awards shows, Reba McEntire would be the belle of the ball. The singer takes her 12th turn as mistress of ceremonies at "The 45th Annual Academy of Country Music Awards."(CBS, 8 p.m.)

MONDAY
Alyssa Milano is one of a quartet of "Romantically Challenged" thirtysomething singles looking for love in this new sitcom. With all due respect to Tony Danza and Judith Light, Ms. Millano will always be the boss to us. (ABC, 9:30 p.m.)

TUESDAY
Ever since the dawn of time -- or at least since the 1970s -- mankind has wondered: Are we alone in the universe? The new series "Ancient Aliens" goes in search of proof that ETs made courtesy calls to Earth in ages past. (History, 8 p.m.)

WEDNESDAY
It's old-home week on "American Idol" as Season 7 winner David Cook (above with Mekdes, 7, of Ethiopia) and Season 4 champ Carrie Underwood join current hopefuls and a host of famous faces for the annual charity fundraiser "Idol Gives Back."(Fox, 8 p.m.)

FRIDAY
Dying is easy, comedy is hard, and the new series "Gravity" seeks the latter in the former as it follows members of a support group for those who have attempted suicide. Krysten Ritter (below), Ivan Sergei and Eric Schaeffer star. (Starz, 10:30 p.m.)

SATURDAY
She's a beloved actress having the best year of her career; of course, we're talking about Betty White, who steals scenes like nobody's business in "The Proposal," the hit 2009 rom-com starring Sandra Bullock and Ryan Reynolds. (Starz, 9 p.m.)

TERMINAL
More than a few weary souls met their end at the hands of Al Pacino in "The Godfather" and "Scarface." Now the actor portrays assisted-suicide advocate Dr. Jack Kevorkian in the seriocomic docudrama "You Don't Know Jack." (HBO, 9 p.m. Sat.)

THIRSTY
Most likely, you turn on your tap, and the H2O flows like, well, H2O. But not everyone is so fortunate. "Nick News Special Edition" takes a kids'-eye look at a global concern: access to clean, safe drinking water. (Nickelodeon, 8:30 p.m. Sun.)

HUNGRY
The documentary series "P.O.V." presents the Oscar-nominated exposé "Food, Inc.," a thought-provoking look at America's massive agricultural-industrial complex. Better to watch this one on an empty stomach. (KCET, 9 p.m. Wed.)